1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * INET		An implementation of the TCP/IP protocol suite for the LINUX
4  *		operating system.  INET  is implemented using the  BSD Socket
5  *		interface as the means of communication with the user level.
6  *
7  *		Definitions for the IP router.
8  *
9  * Version:	@(#)route.h	1.0.4	05/27/93
10  *
11  * Authors:	Ross Biro
12  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13  * Fixes:
14  *		Alan Cox	:	Reformatted. Added ip_rt_local()
15  *		Alan Cox	:	Support for TCP parameters.
16  *		Alexey Kuznetsov:	Major changes for new routing code.
17  *		Mike McLagan    :	Routing by source
18  *		Robert Olsson   :	Added rt_cache statistics
19  */
20 #ifndef _ROUTE_H
21 #define _ROUTE_H
22 
23 #include <net/dst.h>
24 #include <net/inetpeer.h>
25 #include <net/flow.h>
26 #include <net/inet_sock.h>
27 #include <net/ip_fib.h>
28 #include <net/arp.h>
29 #include <net/ndisc.h>
30 #include <linux/in_route.h>
31 #include <linux/rtnetlink.h>
32 #include <linux/rcupdate.h>
33 #include <linux/route.h>
34 #include <linux/ip.h>
35 #include <linux/cache.h>
36 #include <linux/security.h>
37 
38 /* IPv4 datagram length is stored into 16bit field (tot_len) */
39 #define IP_MAX_MTU	0xFFFFU
40 
41 #define RTO_ONLINK	0x01
42 
43 #define RT_CONN_FLAGS(sk)   (RT_TOS(inet_sk(sk)->tos) | sock_flag(sk, SOCK_LOCALROUTE))
44 #define RT_CONN_FLAGS_TOS(sk,tos)   (RT_TOS(tos) | sock_flag(sk, SOCK_LOCALROUTE))
45 
ip_sock_rt_scope(const struct sock * sk)46 static inline __u8 ip_sock_rt_scope(const struct sock *sk)
47 {
48 	if (sock_flag(sk, SOCK_LOCALROUTE))
49 		return RT_SCOPE_LINK;
50 
51 	return RT_SCOPE_UNIVERSE;
52 }
53 
ip_sock_rt_tos(const struct sock * sk)54 static inline __u8 ip_sock_rt_tos(const struct sock *sk)
55 {
56 	return RT_TOS(inet_sk(sk)->tos);
57 }
58 
59 struct ip_tunnel_info;
60 struct fib_nh;
61 struct fib_info;
62 struct uncached_list;
63 struct rtable {
64 	struct dst_entry	dst;
65 
66 	int			rt_genid;
67 	unsigned int		rt_flags;
68 	__u16			rt_type;
69 	__u8			rt_is_input;
70 	__u8			rt_uses_gateway;
71 
72 	int			rt_iif;
73 
74 	u8			rt_gw_family;
75 	/* Info on neighbour */
76 	union {
77 		__be32		rt_gw4;
78 		struct in6_addr	rt_gw6;
79 	};
80 
81 	/* Miscellaneous cached information */
82 	u32			rt_mtu_locked:1,
83 				rt_pmtu:31;
84 
85 	struct list_head	rt_uncached;
86 	struct uncached_list	*rt_uncached_list;
87 };
88 
rt_is_input_route(const struct rtable * rt)89 static inline bool rt_is_input_route(const struct rtable *rt)
90 {
91 	return rt->rt_is_input != 0;
92 }
93 
rt_is_output_route(const struct rtable * rt)94 static inline bool rt_is_output_route(const struct rtable *rt)
95 {
96 	return rt->rt_is_input == 0;
97 }
98 
rt_nexthop(const struct rtable * rt,__be32 daddr)99 static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
100 {
101 	if (rt->rt_gw_family == AF_INET)
102 		return rt->rt_gw4;
103 	return daddr;
104 }
105 
106 struct ip_rt_acct {
107 	__u32 	o_bytes;
108 	__u32 	o_packets;
109 	__u32 	i_bytes;
110 	__u32 	i_packets;
111 };
112 
113 struct rt_cache_stat {
114         unsigned int in_slow_tot;
115         unsigned int in_slow_mc;
116         unsigned int in_no_route;
117         unsigned int in_brd;
118         unsigned int in_martian_dst;
119         unsigned int in_martian_src;
120         unsigned int out_slow_tot;
121         unsigned int out_slow_mc;
122 };
123 
124 extern struct ip_rt_acct __percpu *ip_rt_acct;
125 
126 struct in_device;
127 
128 int ip_rt_init(void);
129 void rt_cache_flush(struct net *net);
130 void rt_flush_dev(struct net_device *dev);
131 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
132 					const struct sk_buff *skb);
133 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
134 					    struct fib_result *res,
135 					    const struct sk_buff *skb);
136 
__ip_route_output_key(struct net * net,struct flowi4 * flp)137 static inline struct rtable *__ip_route_output_key(struct net *net,
138 						   struct flowi4 *flp)
139 {
140 	return ip_route_output_key_hash(net, flp, NULL);
141 }
142 
143 struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
144 				    const struct sock *sk);
145 struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
146 				      struct net_device *dev,
147 				      struct net *net, __be32 *saddr,
148 				      const struct ip_tunnel_info *info,
149 				      u8 protocol, bool use_cache);
150 
151 struct dst_entry *ipv4_blackhole_route(struct net *net,
152 				       struct dst_entry *dst_orig);
153 
ip_route_output_key(struct net * net,struct flowi4 * flp)154 static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
155 {
156 	return ip_route_output_flow(net, flp, NULL);
157 }
158 
ip_route_output(struct net * net,__be32 daddr,__be32 saddr,u8 tos,int oif)159 static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
160 					     __be32 saddr, u8 tos, int oif)
161 {
162 	struct flowi4 fl4 = {
163 		.flowi4_oif = oif,
164 		.flowi4_tos = tos,
165 		.daddr = daddr,
166 		.saddr = saddr,
167 	};
168 	return ip_route_output_key(net, &fl4);
169 }
170 
ip_route_output_ports(struct net * net,struct flowi4 * fl4,struct sock * sk,__be32 daddr,__be32 saddr,__be16 dport,__be16 sport,__u8 proto,__u8 tos,int oif)171 static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
172 						   struct sock *sk,
173 						   __be32 daddr, __be32 saddr,
174 						   __be16 dport, __be16 sport,
175 						   __u8 proto, __u8 tos, int oif)
176 {
177 	flowi4_init_output(fl4, oif, sk ? sk->sk_mark : 0, tos,
178 			   RT_SCOPE_UNIVERSE, proto,
179 			   sk ? inet_sk_flowi_flags(sk) : 0,
180 			   daddr, saddr, dport, sport, sock_net_uid(net, sk));
181 	if (sk)
182 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
183 	return ip_route_output_flow(net, fl4, sk);
184 }
185 
ip_route_output_gre(struct net * net,struct flowi4 * fl4,__be32 daddr,__be32 saddr,__be32 gre_key,__u8 tos,int oif)186 static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
187 						 __be32 daddr, __be32 saddr,
188 						 __be32 gre_key, __u8 tos, int oif)
189 {
190 	memset(fl4, 0, sizeof(*fl4));
191 	fl4->flowi4_oif = oif;
192 	fl4->daddr = daddr;
193 	fl4->saddr = saddr;
194 	fl4->flowi4_tos = tos;
195 	fl4->flowi4_proto = IPPROTO_GRE;
196 	fl4->fl4_gre_key = gre_key;
197 	return ip_route_output_key(net, fl4);
198 }
199 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
200 			  u8 tos, struct net_device *dev,
201 			  struct in_device *in_dev, u32 *itag);
202 int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
203 			 u8 tos, struct net_device *devin);
204 int ip_route_use_hint(struct sk_buff *skb, __be32 dst, __be32 src,
205 		      u8 tos, struct net_device *devin,
206 		      const struct sk_buff *hint);
207 
ip_route_input(struct sk_buff * skb,__be32 dst,__be32 src,u8 tos,struct net_device * devin)208 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
209 				 u8 tos, struct net_device *devin)
210 {
211 	int err;
212 
213 	rcu_read_lock();
214 	err = ip_route_input_noref(skb, dst, src, tos, devin);
215 	if (!err) {
216 		skb_dst_force(skb);
217 		if (!skb_dst(skb))
218 			err = -EINVAL;
219 	}
220 	rcu_read_unlock();
221 
222 	return err;
223 }
224 
225 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
226 		      u8 protocol);
227 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
228 void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u8 protocol);
229 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
230 void ip_rt_send_redirect(struct sk_buff *skb);
231 
232 unsigned int inet_addr_type(struct net *net, __be32 addr);
233 unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id);
234 unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
235 				__be32 addr);
236 unsigned int inet_addr_type_dev_table(struct net *net,
237 				      const struct net_device *dev,
238 				      __be32 addr);
239 void ip_rt_multicast_event(struct in_device *);
240 int ip_rt_ioctl(struct net *, unsigned int cmd, struct rtentry *rt);
241 void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
242 struct rtable *rt_dst_alloc(struct net_device *dev,
243 			    unsigned int flags, u16 type, bool noxfrm);
244 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);
245 
246 struct in_ifaddr;
247 void fib_add_ifaddr(struct in_ifaddr *);
248 void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
249 void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
250 
251 void rt_add_uncached_list(struct rtable *rt);
252 void rt_del_uncached_list(struct rtable *rt);
253 
254 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
255 		       u32 table_id, struct fib_info *fi,
256 		       int *fa_index, int fa_start, unsigned int flags);
257 
ip_rt_put(struct rtable * rt)258 static inline void ip_rt_put(struct rtable *rt)
259 {
260 	/* dst_release() accepts a NULL parameter.
261 	 * We rely on dst being first structure in struct rtable
262 	 */
263 	BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
264 	dst_release(&rt->dst);
265 }
266 
267 #define IPTOS_RT_MASK	(IPTOS_TOS_MASK & ~3)
268 
269 extern const __u8 ip_tos2prio[16];
270 
rt_tos2priority(u8 tos)271 static inline char rt_tos2priority(u8 tos)
272 {
273 	return ip_tos2prio[IPTOS_TOS(tos)>>1];
274 }
275 
276 /* ip_route_connect() and ip_route_newports() work in tandem whilst
277  * binding a socket for a new outgoing connection.
278  *
279  * In order to use IPSEC properly, we must, in the end, have a
280  * route that was looked up using all available keys including source
281  * and destination ports.
282  *
283  * However, if a source port needs to be allocated (the user specified
284  * a wildcard source port) we need to obtain addressing information
285  * in order to perform that allocation.
286  *
287  * So ip_route_connect() looks up a route using wildcarded source and
288  * destination ports in the key, simply so that we can get a pair of
289  * addresses to use for port allocation.
290  *
291  * Later, once the ports are allocated, ip_route_newports() will make
292  * another route lookup if needed to make sure we catch any IPSEC
293  * rules keyed on the port information.
294  *
295  * The callers allocate the flow key on their stack, and must pass in
296  * the same flowi4 object to both the ip_route_connect() and the
297  * ip_route_newports() calls.
298  */
299 
ip_route_connect_init(struct flowi4 * fl4,__be32 dst,__be32 src,int oif,u8 protocol,__be16 sport,__be16 dport,const struct sock * sk)300 static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst,
301 					 __be32 src, int oif, u8 protocol,
302 					 __be16 sport, __be16 dport,
303 					 const struct sock *sk)
304 {
305 	__u8 flow_flags = 0;
306 
307 	if (inet_sk(sk)->transparent)
308 		flow_flags |= FLOWI_FLAG_ANYSRC;
309 
310 	flowi4_init_output(fl4, oif, sk->sk_mark, ip_sock_rt_tos(sk),
311 			   ip_sock_rt_scope(sk), protocol, flow_flags, dst,
312 			   src, dport, sport, sk->sk_uid);
313 }
314 
ip_route_connect(struct flowi4 * fl4,__be32 dst,__be32 src,int oif,u8 protocol,__be16 sport,__be16 dport,struct sock * sk)315 static inline struct rtable *ip_route_connect(struct flowi4 *fl4, __be32 dst,
316 					      __be32 src, int oif, u8 protocol,
317 					      __be16 sport, __be16 dport,
318 					      struct sock *sk)
319 {
320 	struct net *net = sock_net(sk);
321 	struct rtable *rt;
322 
323 	ip_route_connect_init(fl4, dst, src, oif, protocol, sport, dport, sk);
324 
325 	if (!dst || !src) {
326 		rt = __ip_route_output_key(net, fl4);
327 		if (IS_ERR(rt))
328 			return rt;
329 		ip_rt_put(rt);
330 		flowi4_update_output(fl4, oif, fl4->flowi4_tos, fl4->daddr,
331 				     fl4->saddr);
332 	}
333 	security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
334 	return ip_route_output_flow(net, fl4, sk);
335 }
336 
ip_route_newports(struct flowi4 * fl4,struct rtable * rt,__be16 orig_sport,__be16 orig_dport,__be16 sport,__be16 dport,struct sock * sk)337 static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
338 					       __be16 orig_sport, __be16 orig_dport,
339 					       __be16 sport, __be16 dport,
340 					       struct sock *sk)
341 {
342 	if (sport != orig_sport || dport != orig_dport) {
343 		fl4->fl4_dport = dport;
344 		fl4->fl4_sport = sport;
345 		ip_rt_put(rt);
346 		flowi4_update_output(fl4, sk->sk_bound_dev_if,
347 				     RT_CONN_FLAGS(sk), fl4->daddr,
348 				     fl4->saddr);
349 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
350 		return ip_route_output_flow(sock_net(sk), fl4, sk);
351 	}
352 	return rt;
353 }
354 
inet_iif(const struct sk_buff * skb)355 static inline int inet_iif(const struct sk_buff *skb)
356 {
357 	struct rtable *rt = skb_rtable(skb);
358 
359 	if (rt && rt->rt_iif)
360 		return rt->rt_iif;
361 
362 	return skb->skb_iif;
363 }
364 
ip4_dst_hoplimit(const struct dst_entry * dst)365 static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
366 {
367 	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
368 	struct net *net = dev_net(dst->dev);
369 
370 	if (hoplimit == 0)
371 		hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
372 	return hoplimit;
373 }
374 
ip_neigh_gw4(struct net_device * dev,__be32 daddr)375 static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
376 					     __be32 daddr)
377 {
378 	struct neighbour *neigh;
379 
380 	neigh = __ipv4_neigh_lookup_noref(dev, (__force u32)daddr);
381 	if (unlikely(!neigh))
382 		neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
383 
384 	return neigh;
385 }
386 
ip_neigh_for_gw(struct rtable * rt,struct sk_buff * skb,bool * is_v6gw)387 static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
388 						struct sk_buff *skb,
389 						bool *is_v6gw)
390 {
391 	struct net_device *dev = rt->dst.dev;
392 	struct neighbour *neigh;
393 
394 	if (likely(rt->rt_gw_family == AF_INET)) {
395 		neigh = ip_neigh_gw4(dev, rt->rt_gw4);
396 	} else if (rt->rt_gw_family == AF_INET6) {
397 		neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
398 		*is_v6gw = true;
399 	} else {
400 		neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
401 	}
402 	return neigh;
403 }
404 
405 #endif	/* _ROUTE_H */
406